Recent advances in high-speed broadband wireless access systems have introduced a capability of running several frequency carriers across multiple frequency bands.
In the context of this invention, the following definitions shall apply:
Frequency band: a range of frequencies for transmitting data; examples: frequency band A from 900-1000 MHz, frequency band B from 1800-1900 MHz, frequency band C from 2100-2200 MHz.
Frequency Carrier: a range within a frequency band; example: in W-CDMA, a carrier typically has a bandwidth of 5 MHz.
Radio Frequency (RF) Receiver: hardware device capable to operate in certain frequency bands and able to operate up to n carriers simultaneously.
The high-speed packet access (HSPA) as specified by the 3rd Generation Partnership Project (3GPP), supports up to two frequency carriers in two frequency bands according to HSPA release 9 (Rel-9) and up to four frequency carriers in two frequency bands according to HSPA release 10 (Rel-10). With regard to HSPA release 11 (Rel-11), up to eight carriers in two frequency bands are supported.
A user equipment (UE), complying with HSPA from Rel-9 onwards, can support the capability for inter-frequency measurements for the dual-band case. For supporting several carriers across multiple bands, a so-called multi-band UE would therefore comprise at least two RF receivers with at least one receiver for supporting reception and measurement on one frequency band.
With regard to inter-frequency measurements, necessary e.g. in the context of inter-frequency handovers, the so-called Compressed Mode (CM) is applied in case the UE is not capable of measuring a cell simultaneous with all its ongoing reception activities. According to the current specification, the compressed mode configuration applies to all the configured bands and carriers of the UE. Therefore, data interruption due to transmission gaps, which are used for said measurements, happens to all the configured carriers, irrespective of the bands the carriers are operating in, and independent on the UE's capabilities.